- Build Agent needs to run a physical x64 Windows 8.1 based machine to be able to run Phone emulators
- Setup build agent to run as an interactive process and enable it to run unit tests (obtain developer license). Check this MSDN page for more help on this.
- Install Visual Studio 2013 + Update 2 (with support for Phone development) on Build Agent
Once you have these, you can use custom scripts in TFS 2013 build definition to run phone tests using vstest.console command line. See the script RunPhoneTests.bat